Dam



May 15, 1923. 1,455,092 F. A. NOETZLI y DAM Filed ot, 2s. 1920 Patented Mayv 15, 1923.

UNITED stares l,455,tl92 l harem' ortica.

FRED A. NOETZLT, OF BERKELEY, CALIFORNIA.

" DAM.

Application le'd October 23, 1920. Serial No. 418,897.

To all whom t may concern Be it known that I, FRED A. Nonrzm, a citizenof Switzerland, residing at Berkeley,

in the county of Alameda and State of California, have invented new and useful Tm'- provements in Dams, of which the following f 'place of greatest weakness 'and uncertainty.

with regard to strength has been in the buttresses and although the stresses inthe arches proper may be accurately determined by means of the theory of the elastic arch,

"the stability of thefbuttresses is very uncertain particularly in the case of high dams. Attempts have been made "to stiften the' slender vertical buttress walls by `bracing them against each other and whil'ethis may be safe enough in dams not over 100 to 120 feet in height and under ordinary load 'conditions, the economical height of such dams being limited to about 120-130 ft., for dams higher than this the cost of bracing between the buttresses becomes excessive and makes such bracing prohibitive; or even if braced, these buttresses are not apt to be suiiiciently stable. Also, if such a dani due to an exceptionally large flood, is subjected to overflow, because of inadequacy of th'e spillway or some other cause, blocks of ice, logs, or the falling water itself, might destroy such braces, and the thin high buttress walls are apt to buckle out and lead to the destruction of the dam. Again, should one of the individual arches accidentally cave in, the falling dbris and the onrushing water would exert such an impact against the braces that these members, which generally are strongly reinforced with steel bars, might tear down the adjacent buttresses. i

Further, in the present types of multiple arch dams, all the buttresses .have the top at about the same elevation and the arches between two neighboring buttresses have a substantially constant upstream radius.

The objects of my invention are, first, tobuild every'buttress so stiff that true column action will occur without danger of buckling, thus making any kind of lateral braclng between the buttresses unnecessary, second, to provide truss-like'` supports be* tween the buttresses for the purpose of supporting the falsework for the upper parts of a very high multiple arch dam during construction; so as to effect a saving in lumber usually required lto build the false work from the ground to the top of the dam.`

In the accompanying drawing in which my improved dam is illustrated, Figure l is a partial horizontal sectional viewof a `typical portion of the dam. Figure 2 is a vertical cross section on the lin'e 2 2 of ;Figure 1.` `Figure 3 is a rear elevation of a portion of the dam illustrated by Figi.. l

showing'the truss-like bracing of the buttresses. l

Referring to` the embodiment of the invention shown in Figures l, 2 and 3 the multiple-arch concrete dam is made upy of substantially circular arches 1, abutting and` y joining with buttresses 2. The buttressesl 2 consist in `the main of two parallel walls braced against' each other by cross-walls or braces l. The distance between the walls 3 of each buttress considering it a vertical column, issuch that all possibility of lateral buckling is removed. This safeguard afrainstlateral buckling may be increased by p acing reinforcing bars 5, near the outer surface of the walls and it will be particular advantage to tie such bars together by means of cross-bars 6, so as to form an interconnected reinforcing structure of great strength. The down-stream ends of the two buttress walls 3 are preferably connected b v a cross-wall 8. This cross-wall may be reinforced by longitudinal bars 9, connected by transverse bars l0, so as to form a reinforcing structure of great strength. There may be provided small span walls 11, between the walls of the buttresses at up-stream ends of said buttress walls and these small walls are preferably in the form of arches particularly if the distance between the buttress walls should be comparatively large, otherwise they may be straight.

In case of great heights of such overiiow dams I may provide a water-cushion for .the falling water by building a secondary low dam 12 between the down-stream ends of the buttresses.

I may provide truss-like braces 13 between the buttresses 2. For very1 high multiple arch dams the cost of the falsework becomes a very important item because the `.stiifen the buttresses inthe finished struc- Yim'ents are produced.

ture;y

In hingeless arches which are subject to deformations due to compression, shrinkage, change of temperature, etc., bending nio- Such bendingl moments are ltwice as largepat the abutments than at'the crown. They are zero at a distance of about one-third of the rise of the archl from the crown. To produce an .arch of as nearly uniform strength as vpracn ticable, the thickness of such an arch has to `be increased in the immediate proximity'.

of the Xed abutments.

In the arches of my improved dam, the

thickness is substantially uniform from the crown to about one-half of the distance between crown and haunches and from there the thickness is increased until the theoretically desired thickness at the abutments ,is`

reached. A very satisfactoryl method of doing this consists in keeping the radius of the extrados ofthe arch constant-throughout and makingthe intrados a threeor four-centered arc, substantially as shown in Fig. l.

I claim:

1. Iny a multiple arch dam the combination of arches and buttresses, said buttresses having two separate walls and braces between said walls.

2. A multiple arch darn7 having buttresses with two separate mainwalls and cross walls near the down-stream end of said buttresses and reinforcing bars "near the intersection between said main walls and said cross walls, said reinforcing bars being connected together; s 1

3. A multiple arch dam, havingbu'ttresses withtwo main walls, Acrosswalls between said main walls, reinforcing bars near the intersection between said mainwalls and said cross walls, said reinforcing bars being connected together. e

4. In a multiple -arch dam the combination with buttresses, of arches between said buttre'ssesandsmaller arches near the upstream ends of said buttresses.

5. Ina multiple arch dam the combina tion with alternating long span and short span arches, of buttress walls supporting said arches and braces between said walls..

6A In a buttressed `darn the combination with alternating ,archesl and span walls, of buttress'walls supporting `said. arches and said span walls, and braces between said buttress walls.

FRED A. NOETZLI. 

